This invention relates to electromechanical systems, and more particularly to microelectromechanical systems and methods.
Microelectromechanical (MEMS) technology has been used in a wide range of applications. For example, MEMS devices can be used to switch optical energy from the switch inputs to selected switch outputs. MEMS optical switches, sometimes referred to as Optical Cross-Connect (OXC) switches can include an Nxc3x97N array of reflectors to reflect optical energy from any switch input to any switch output. For example, in a 2xc3x972 OXC, a selected reflector of the 2xc3x972 array can be used to reflect the optical energy from any switch input to any switch output.
Some conventional MEMS OXC switches operate by orienting the reflectors horizontally (in the plane of the substrate on which the reflector is located) in a non-reflecting position and vertically (orthogonal to the substrate) in a reflecting position. Therefore, to switch optical energy from an input of the OXC switch to an output thereof, the selected reflector can be oriented vertically and the other reflectors are oriented horizontally.
Unfortunately, reflectors in some MEMS OXC switches may occupy a relatively large portion of the substrate, thereby reducing the number of reflectors that may be included in the MEMS OXC switch. For example, some MEMS OXC switches orient the reflectors in a horizontal position when the reflectors are in a non-reflective position as described above. Accordingly, the substrate may be over-sized to provide adequate space for all of the reflectors to be oriented horizontally on the substrate. Furthermore, magnetically actuated MEMS OXC switches may have localized magnetic actuators located under each reflector. The localized magnetic actuators may, therefore, further increase the area of the substrate which may need to be allocated to each reflector.
Other conventional MEMS optical switches can be configured to use in-plane reflectors where the inputs and outputs to the optical switch are positioned on opposite sides of the device. This configuration may require the fibers for the inputs to be aligned with the fibers for the outputs on the opposite side. In other conventional MEMS optical switches, the reflectors can be configured perpendicular to a plane of the device where the fibers for the inputs and outputs are placed in predefined channels on the device die. In this configuration, however, the reflectors may be difficult to fabricate. Thus, there continues to be a need to further improve MEMS optical switches.
Pursuant to embodiments according to the present invention, the inputs and outputs of a MEMS optical switch are obliquely angled towards and away from a face thereof and adjacent thereto. A moveable reflector is configured to be moved from a first position to a second position, that is parallel to the first position, to switch optical radiation from the inputs to the outputs. Having the inputs and outputs obliquely angled towards and away from the same face and adjacent thereto may reduce the size and/or the complexity of packaging the optical switch. Accordingly, the cost of the optical switch may be reduced.
In some embodiments according to the present invention, a MEMS optical switch includes a substrate having first and second opposing faces and at least one side therebetween. An input is obliquely angled towards the first face adjacent thereto. The input optically couples optical radiation towards the first face. A movable reflector on the first face moves from a first position to a second position that is parallel to the first position to reflect the optical radiation from the input to provide reflected optical radiation. An output is obliquely angled away from the first face adjacent thereto. The output optically couples the reflected optical radiation away from the first face.
In some embodiments according to the present invention, the moveable reflector moves between the first and second positions in a direction that is parallel to the first face. In some embodiments according to the present invention, the MEMS optical switch includes a member that extends in a direction on the first face and that is coupled to the moveable reflector. An actuator on the first face is coupled to the member. The actuator moves the moveable reflector between the first and second positions in the direction parallel to the first face.
In some embodiments according to the present invention, a thickness of a reflective portion of the moveable reflector that reflects the optical radiation is less than a thickness of the member. In some embodiments according to the present invention, the reflective portion comprises a metal and the member comprises silicon.
In some embodiments according to the present invention, the MEMS optical switch further includes a member on the first face that is coupled to the moveable reflector and an actuator on the first face that is coupled to the member. The actuator rotates the member in a direction that is parallel to the first face to move the moveable reflector between the first and second positions.
In some embodiments according to the present invention, the MEMS optical switch further includes a reflector on the first face and the moveable reflector is cantilevered over the reflector in the second position. In some embodiments according to the present invention, the MEMS optical switch further includes a recess in the first face and the reflector is in the recess.
In some embodiments according to the present invention, the reflected optical radiation is first reflected optical radiation and the output is a first output. The MEMS optical switch further includes a reflector on the first face beneath the moveable reflector. The reflector reflects the optical radiation from the input when the moveable reflector is in the first position to provide second reflected optical radiation. The MEMS optical switch further includes a second output that is obliquely angled away from the first face adjacent thereto. The second output optically couples the second reflected optical radiation away from the first face. In some embodiments according to the present invention, the MEMS optical switch further includes a nonreflecting recess in the first face aligned with the moveable reflector in the second position.
In method embodiments according to the present invention, the MEMS optical switch is formed by forming a member on a first face of a substrate. A recess is formed in the first face of the substrate adjacent to the member by etching around the member. A reflector is formed in the recess. A first reflective surface is formed on a first side of the member that faces away from the reflector. The substrate and the reflector are etched through from a second face of the substrate that is opposite the first face to expose a second side of the member opposite the first side. A second reflective surface is formed on the second side of the member that faces towards the reflector.
In some embodiments according to the present invention, the etching around the member includes wet etching around the moveable member. In some embodiments according to the present invention, the member is at least one of polysilicon, silicon rich nitride, and crystallized silicon.
In some embodiments according to the present invention, the forming a first reflective surface on the member includes etching a portion of the member using deep reactive ion etching. In some embodiments according to the present invention, the substrate is etched through to form a hole aligned to an initial position of the member. In some embodiments according to the present invention, the hole is elongated in a direction in which the member is configured to move.